It is generally known that a gasket may be inserted between the cover and the neck of the opening of a container or drum to effect a seal which prevents the contents of the drum from flowing out, even if relatively high surge pressures result for example, when a drum is toppled from a stack. However, the gasket may be overstressed or destroyed by squeezing when the drum topples on to its cover or when high axial loads occur. U.S. Pat. No. 4,177,934 to Hammes et al. for Container and Lid disclosed a container which avoids this difficulty by providing abutting container and cover flanges to limit the motion of the cover.
In internal pressures are high enough when a drum topples the sealing ability of the gasket can be briefly overcome, and at the moment that the toppling drum strikes, a small amount of the contents of the drum can emerge. While this loss may be neglible as compared to the total volume of the drum, if the drum is filled with a hazardous material, such emergence of fluid is intolerable.